From the past, there has been a coil component in which a position of a magnetic core with respect to a coil is changed by an external signal such that the inductance value of the coil can be changed. Such a coil component includes a coil, a magnetic core, a movable core which is used as a portion of the magnetic core and which changes the relative position with respect to the magnetic core, and an actuator for changing the position of the movable core. For the actuator, there is used a monomorph type or bimorph type piezoelectric device. The movable core is connected to a tip portion of the piezoelectric device. When a drive voltage is applied to the piezoelectric device, a piezoelectric body constituting the piezoelectric device expands and contracts and the relative position of the movable core with respect to the magnetic core changes. Consequently, it is possible to adjust the inductance value of the coil component.
In Patent Document 1, there is a description with respect to a coil component including a bimorph type piezoelectric device. In a state of not driving the piezoelectric device, a movable core portion bonded to the tip portion of the piezoelectric device is perfectly combined with the periphery core portion. When a voltage is applied to this piezoelectric device, the piezoelectric body is bent and deformed toward the direction moving away from the core portion. When the movable core portion moves toward the same direction as that of the piezoelectric body, a gap between the movable core portion and the core portion becomes larger, so that the inductance value becomes smaller.
In Patent Document 2, there is a description with respect to a variable inductance device for changing the inductance value by changing the relative position of two cores owing to an action of a piezoelectric actuator which uses a monomorph type piezoelectric device.